The NTSB says air traffic control communications and radar data show the plane flew south, climbing to 4,800 feet. The last radio contact came when a controller approved a radio frequency change, which Stack acknowledged by saying, "Thanks for your help. Have a great day."

At 9:54 a.m., radar tracked the aircraft descending from 4,800 feet and turning west. At 9:57 a.m., the last radar contact showed the plane flying southwest at 1,000 feet before disappearing.

The aircraft was destroyed on impact into the office building. The NTSB says the FBI has taken over the investigation.